The following is a tabulation of some prior art that presently appears relevant:
U.S. patentsPat. No.Issue DatePatentee5,791,062Aug. 8, 1998Walker6,944,963Sep. 20, 2005Amaru7,281,337Oct. 16, 2007Oehlke & Moen7,383,640Jun. 10, 2008Barry7,946,042May 24, 2011Williams
U.S. Pat. application PublicationsPublication NumberPublication DateApplicant2011/0005441 A1Jan. 13, 2011Roche
As an exemplary sewing product, quilts are a finished fabric product typically consisting of three layers: the top fabric or quilt top, backing material and batting (filler, sandwiched between the top and backing materials to give the quilt loft). The quilt tops are generally formed by piecing together multiple quilt blocks. The quilt blocks typically are assembled from multiple pieces of fabrics with contrasting colors and/or textures which are arranged in a geometric pattern which is pleasing to the eye.
Traditional means to fabricate the quilt blocks are a three-step process: (1) selecting one or more quilt block patterns and fabrics; (2) measuring and cutting fabrics into pieces which will form the quilt block patterns; (3) assembling the pieces by seaming to form the quilt block. Seaming is a sewing method used to join two pieces of fabric together in which the fabrics are overlapped slightly (requiring seam allowance) and stitched together with a needle and thread either by hand or with a sewing machine. The most desirable seam is “hidden” in the sense that it is hidden when viewed from the preferred presentation side of the finished quilt. A hidden seam is produced by inverting one of the pieces of fabric to be joined before the seam is sewn. After the seam is sewn the fabric is folded back, reversing the inversion and leaving the cut edges of both pieces of fabric which have been joined entirely on one side of the finished piece.
In preparing quilt blocks, for example, it has traditionally been difficult to assemble pattern units having curved or other free-form geometric shapes for the following reasons: (1) curved lines traced onto fabric and then cut by hand are frequently imprecise and variable which degrades the esthetic quality of each quilt block and leads to cumulative errors which degrade the geometric precision of assembly of the overall quilt; (2) the necessity of having a seam allowance means that the two pieces of fabric to be joined cannot be cut along a common cutting line, but must instead be cut separately to different shapes; (3) seaming curved pieces of fabrics creates tensions along the seam which cause the joined pieces fabric to bunch and fold in an unseemly fashion; and (4) when seaming along a curved path it is challenging to keep the excess fabric out of the way of the way when stitching along the seam.
Additionally, many quilt blocks possess geometric symmetry. It is desirable to take advantage of this symmetry by joining two pieces of fabric and then cutting them along one or more lines of symmetry to produce several pattern units simultaneously. Traditionally, quilt blocks which are fabricated by hand do not take advantage of this symmetry, resulting in the need to mark and cut all pieces individually.
There have been many prior art attempts to overcome these limitations, some of which have been patented as below.
U.S. Pat. No. 5,791,062 (Walker), U.S. Pat. No. 6,944,963 (Amaru), U.S. Pat. No. 7,281,337 (Oehlke and Moen), U.S. Pat. No. 7,383,640 (Barry) and U.S. Pat. No. 7,946,042 (Williams) attempt to overcome these limitations by using rigid templates which indicate the locations for sewing and cutting. These approaches suffer because the types and sizes of curved elements are restricted to those inherent in the template, which do not afford the quilter free choice to select a curved path which is desirable to them based on esthetics or to conform to a pre-existing quilting pattern. U.S. Pat. No. 5,791,062 (Walker) is limited to providing a template which guides the cutting of fabric using a hand cutting device such as a rotary cutter along a pre-determined number of curves which consist of portions of circles with a limited number of pre-determined radii. U.S. Pat. No. 6,944,963 (Amaru) and U.S. Pat. No. 7,383,640 (Barry) are similar except that in each case the template described provides a limited number of repeating undulating contours. U.S. Pat. No. 7,946,042 (Williams) is a template that is a variation of a drafter's compass, and is limited to facilitating the construction of a specific quilting pattern known as the Mariner's Compass star which is constructed in part out of curves which consist of portions of circles. U.S. Pat. No. 7,281,337 (Oehlke and Moen) describe a template which assists in the joining of fabric; however the template is limited to joining fabrics along straight lines.
Other art is known in commercial product offerings. For example, the Curve Master Presser Foot™ is a commercial product that facilitates the joining of fabric along curved seams, but is difficult to use in practice as evidenced by the number of hints included in the directions and the need to use a special set of bent tip tweezers. Furthermore the Curve Master Presser Foot™ offers no assistance in the cutting of fabric or in producing many pattern units simultaneously.
The Accuquilt Go! Fabric Cutter™ cuts fabric using a press and die. Available dies include curved shapes suitable for sewing curved seams. The Accuquilt Go! Fabric Cutter™ suffers because a unique die must be used for each desired shape. The quilter must choose a curved path from among a limited number of choices defined by the dies which are available, and is unable to modify the curve based on esthetic desire or the need to conform to a pre-existing pattern.
Many guides and instructions available to quilters attempt to overcome the difficulty of producing curved seams by using ‘workarounds’. These workarounds compromise the perceived artistry of the finished quilt. One common workaround is to simplify the task of joining the pieces by using a simple top or more decorative applique stitch. Layers of fabric are laid on top of each other and sewn together without inverting one of the pieces of fabric being joined. Since the fabric is not inverted the thread of the seam and an edge of one of the pieces of joined fabric are visible on each side of the finished piece.
Additional related art is described in U.S. Patent Application 2011/0005441 (Roche). Fabrication of quilt blocks is facilitated by use of an embroidery machine. A quilter retrieves a digitized embroidery file that is fed into an embroidery machine. The file instructs the embroidery machine to stitch quilt layers together according to a pre-determined pattern. The art teaches that the layers shall be in the form of one or more applique layers applied to a base layer with a tack down stitch. No provision is provided for generating curved seams by using the embroidery machine in combination with appropriate instructions in the digitized embroidery file.